Ruthenium complexes and processes for their preparation

ABSTRACT

THE INVENTION PROVIDES NEW RUTHENIUM COMPLEXES OF THE FORMULA   RU(DIKET)2LN   IN WHICH (DIKET REPRESENTS A BIDENTATE LIGAND DERIVED FROM A B- DIKETONE AND HAS THE GENERAL FORMULA:   R1-CO-C(-R2)=C(-R3)-O(-)   IN WHICH R1, R2 AND R3 ARE EACH ALKYL OR 1 TO 3 CARBON ABOMS, PHENYL RO NAPHTHYL, OR R2 IS HYDROGEN, OR R1 AND R2 TOGETHER FORM A TRI- OR TETRA-METHYLELE CHAIN WHICH IS UNSUBSTITUTED OR SUBSTITUTED BY ALKYL OF 1 TO 3 CARBON ATOMS, OR R1 AND R3 TOGETHER FORM A DI- OR TRI-NETHYLENE CHAIN WHICH IS UNSUBSTITUTED OR SUBSTITUTED BY AN ALKYL GROUP OF 1 TO 3 CARBON ATOMS AND L IS A NITRILE LIGAND, WHICH ARE USEFUL AS CATALYSTS IN, FOR EXAMPLE ISOMERIZATIONS (SUCH AS THE REPPE SYNTHESIS), HYDROGENATIONS, AND DIMERIZATIONS (SUCH AS HYDRODIMERIZATION OF ACRYLONITRILE TO ADIPONITRILE).

United States Patent 3,804,869 RUTHENIUM COMPLEXES AND PROCESSES FORTHEIR PREPARATION Pierre Chabardes and Louis Colevray, Lyons, France,assignors to Rhone-Poulenc S.A., Paris, France No Drawing. Continuationof abandoned application Ser.

No. 782,769, Dec. 10, 1968. This application May 24, 1972, Ser. No.256,424

Claims priority, application France, Dec. 11, 1967,

Int. Cl. C07f 15/00 US. Cl. 260-429 J Claims ABSTRACT OF THE DISCLOSUREThe invention provides new ruthenium complexes of the formula:

Ru(diket) L in which (diket) represents a bidentate ligand derived [froma fl-diketone and has the general formula:

in which R R and R are each alkyl of 1 to 3 carbon atoms, phenyl ornaphthyl, or R is hydrogen, or R and R together form a triortetra-methylene chain which is unsubstituted or substituted by alkyl of1 to 3 carbon atoms, or R and R together form a dior tri-methylene chainwhich is unsubstituted or substituted by an alkyl group of 1 to 3 carbonatoms and L is a nitrile ligand, which are useful as catalysts in, forexample, isomerizations (such as the REPPE synthesis), hydrogenations,and dimerizations (such as the hydrodimerization of acrylonitrile toadiponitrile).

CROSS-REFERENCE TO RELATED APPLICATIONS This is a continuationapplication of our earlier application Ser. No. 782,769, filed Dec. 10,1968 and now abandoned.

This invention relates to new ruthenium complexes, I

Numerous ruthenium complexes which contain ligands 1 derived from.B-diketones and halogen ligands are known. For example, British patentspecification No. 956,242 describes the following chloro complexes: (5,6dimethyl- 1,10 phenanthroline) (acac)RuCl,(4,4'-diethyl-2,2'-bipyridino) (acac)RuCl, (4,4-diethyl 2,2 bipyridino)(acac) RuCl.

Two ruthenium complexes, containing ligands derived from j3-diketones,which contain no halogeno or carbonyl ligands have been described in theliterature (Dwyer et al. Austr. J. Chem, 16, 49 (1963)). These are:(2,2-bipyridino) (aca Ru and (o-phen) (acac) Ru (where (acac) and(o-phen) are used herein to denote the acetylacetonato and1,10-phenanthroline ligands, respectively).

According to the present invention, there are provided rutheniumcomplexes of the general formula:

3,804,869 Patented Apr. 16, 1974 in which (diket) represents a bidentateligand derived from a p diketone and has the general formula:

in which R R and R each represent alkyl, cycloalkyl or aryl groups whichmay be substituted by halogen and wherein R and R or R and R takentogether, may represent a divalent hydrocarbyl radical which may besubstituted by halogen or R may be hydrogen; L is a monoor bi-dentateligand other than (diket), CO, 2,2- bipyridino or (o-phen) derived froman organic compound capable of donating one or more pairs of electronsand n is 1 or 2.

Preferred (diket) ligands are those in which R R and R are each loweralkyl, phenyl or naphthyl, or R and R or R and R together form a triortetra-methylene chain which may be substituted by lower alkyl.

Examples of the ligand (diket) include:

acetylacetonato,

2,4-hexanedionato, 2,4-heptanedionato, 5-methyl-2,4-hexanedionato,3,5-heptanedionato,

1, 1, 1-trifiuoro-2 pentanedionato, benzoylacetonato,1,3-diphenyl-1,3-propanedionato, I,1,1-trifluoro-2-benzoylacetonato,fi-isonaphthoyl- 1 1,1-trifiuoroacetonato, 3-methyl-2,4-pentanedionato,1,3-cyclopentanedionato, 1,3-cyclohexanedionato,5,5-dimethyl-1,3-cyclohexanedionato, Z-acetylcyclohexanonato and1,8-hexahydronaphthalenedionato.

Examples of the ligand L may be taken from organic compounds which arecapable of donating one or more pairs of electrons, particularlymonoamines or polyamines such as methylamine, ethylamine,cyclohexylamine and ethylenediamine; aldehydes such as formaldehyde,acetaldehyde and benzaldehyde; imines such as acetaldimine; amides suchas dimethylformamide and propionamide; nitriles such as propionitrile,acetonitrile and acrylonitrile; tertiary phosphines such astriphenylphosphine; tertiary arsines and stibines; monoolefinic orpolyolefinic compounds such as for example cyclooctadienes; andheterocyclic bases such as pyridine.

The complexes of the invention may be prepared by the followingprocesses.

In the first process, the ligand L is reacted, in the presence of ahydrogenation catalyst, with a tris(di-ket)-Ru complex under anatmosphere containing hydrogen.

A solvent may be present and may be, for example, a liquid aliphatichydrocarbon, such as pentane or hexane, a liquid cycloaliphatichydrocarbon such as cyclohexane, an aromatic hydrocarbon such as benzeneor an ether such as 2-methoxyethane or dioxane. If the ligand L is inthe liquid state under the reaction conditions it may be used assolvent.

The hydrogen pressure employed is not critical though a very lowpressure will give an uneconomically slow reaction while a very highhydrogen pressure may reduce certain of the ligands employed, forexample, when L is nitrile. Preferred hydrogen pressures are from 5 tobars.

The hydrogenation catalyst employed may be any catalyst employed inhydrogenation reactions. However, to avoid introducing metals other thanruthenium into the reaction system (which may form complexes differentfrom those required and may contaminate the required complexes) it ispreferred to use a ruthenium catalyst. Hydrated ruthenium oxide RuO(OH)has proved a particularly valuable catalyst in this process. The amountof catalyst employed is not critical: it is possible to work with anamount of a ruthenium-containing catalyst equal to 0.001 to 10% byweight of the ruthenium contained in the reagent tris(diket)Ru complex.This amount may be increased to more than 10% but such an amount givesno additional advantage and is uneconomic.

The reaction temperature is not critical and may vary within a widerange, for example from 20 to 150 0., depending on the reagents used.

In the second process the ligand L is introduced into the complex by aligand exchange process in which complexes of the formula (diket) RuLwhere L' differs from the required ligand L in being a Weaker electrondonor, are reacted with the required ligand L to give the requiredcomplex (diket) RuL This exchange process may take place in an inertsolvent, for example one of those exemplified in the first process;likewise, if the ligand L is liquid under the reaction conditions it maybe employed as solvent.

When working in an inert solvent the amount of (diket) RuL' and Lemployed may be close to the stoichiometric quantities or within aslight excess of L; if L is being used as solvent it will be in excess.

The two processes may also be used to prepare the known compounds(2,2'-bipyridino)(acac) Ru and (o-phen) (acac) Ru The rutheniumcomplexes of the invention may be employed as catalysts in many organicreactions such as isomerization, oligomerizations, for example the REPPEsynthesis, hydrogenations and dimerizations, particularlyhydrodimerization of acrylonitrile to adiponitrile.

The following Examples 1 to illustrate the invention:

EXAMPLE 1 g. of Ru(acac) 0.1 g. of RuO(OH) 335 cm of anhydrous benzeneand 335 cm. of acetonitrile were introduced into a one litre autoclave.

The apparatus was purged with nitrogen and hydrogen was then introducedunder a pressure of 10 bars. The mixture was heated to 60 C. for 16hours and cooled; the gas was released from the apparatus, the productfiltered and the filtrate concentrated under reduced pressure. 10.57 g.of a solid product of an orange-brown color remained and were extractedin a Soxhlet with diethyl ether. An etherial solution containing 5 g. ofunconverted ruthenium acetylacetonate was obtained and 4.39 g. of solidcomplex of formula (acac)- Ru(CH CN) remained in the Soxhlet. The yield,relative to ruthenium acetylacetonate consumed, is 92%.

EXAMPLE 2 0.5 g. of recrystallized Ru(acac) 0.005 g. of RuO(OH) 25 cm.of anhydrous benzene and 25 cm. of propionitrile were introduced into a125 cm. autoclave.

The hydrogen pressure was adjusted to 10 bars. The mixture was heated to90 C. for 16 hours and then cooled, the gas was released from theapparatus, the product filtered, the filtrate evaporated and the residuefrom the evaporation washed with 50 cm. of ether. A solid brown complexof formula Ru(acac) (CH CH -CN) was obtained in a yield of 18%.

EXAMPLE 3 0.49 g. of Ru(acac) 10 cm. of pyridine and 0.005 g. of RuO(OH)were introduced into a 125 cm. autoclave, followed by hdrogen up to apressure of 10 bars.

4 The mixture was heated to 100 C. for 15 hours and then cooled, the gaswas released from the apparatus, the product filtered, the filtrateevaporated and the evaporation residue washed with pentane. Abrownish-orange complex of formula Ru(acac) (C H N) was obtained in ayield of 86%.

EXAMPLE 4 0.3 g. of Ru(acac) (CH CN) and 10 cm. of pyridine wereintroduced into a three-necked 50 cm. flask fitted with a stirrer, acondenser and a nitrogen inlet.

The solution was stirred under reflux for 20 hours, then concentrated todryness, and the solid residue washed with pentane; 0.32 g. of abrownish-orange solid complex of formula Ru(acac) (C H N) were thusobtained in a yield of 90%.

EXAMPLE 5 0.38 g. of Ru(acac) (CH CN) 10 cm. of ethanol and 0.54 g. oftriphenylphosphine were introduced into a three-necked 50 cm. flaskfitted with a stirrer, a condenser and a nitrogen inlet.

An emulsion was obtained which was heated under reflux for 21 hours.After cooling the mixture was filtered and the residue washed with 40cm. of cyclohexane and then with pentane. A complex of formula wasobtained in a yield of 48.5%.

The following Examples 6 and 7 illustrate the preparation of knowncompounds by the process of the invention.

EXAMPLE 6 0.38 g. of Ru(acac) (CH CN) 0.16 g. of a,a'- bipyridyl, and 20cm. of ethanol were introduced into a three-necked 50 cm. flask fittedwith a condenser, a stirrer and a nitrogen inlet.

The mixture was heated under reflux for 22 hours, then cooled, filtered,and the filtrate evaporated. 0.4 g. of a chestnut-black solid were thusobtained and were recrystallized from a mixture of benzene and petroleumether.

A complex of formula (2,2'-bipyridino) (acac) Ru was obtained in a yieldof 88%.

EXAMPLE 7 0.38 g. of Ru(acac) (CH CN) 0.19 of 1,10-phenanthroline and 20cm. of methoxyethanol are introduced into a three-necked 50 cm. flaskfitted with a stirrer, a condenser and a nitrogen inlet.

The mixture is heated to C. for two hours and then evaporated todryness, and the residue is washed with hexane and then with pentane.0.44 g. of a brownishblack complex of formula (o-phen) (acac) Ru wereobtained, this figure representing a yield of 93%.

We claim: 1. A ruthenium complex of the formula:

Ru(diket) 1.

in which (diket) is a bidentate ligand and has the for mula:

in which R R and R are each methyl, ethyl, n-propyl, isopropyl, phenylor naphthyl, and R can also be hydrogen, or R and R together form atrior tetra-methylene chain which is unsubstituted or substituted byalkyl of 1 to 3 carbon atoms or R and R together form a diortri-methylene chain which is unsubstituted or substituted by methyl,ethyl, n-propyl or isopropyl, and L is a nitrile ligand.

2. A ruthenium complex according to claim 1 in which (diket) is selectedfrom the class consisting of acetylacetonato, 2,4-hexanedionato,2,4-heptanedionato, S-methyl- 2,4-hexanedionato, 3,5-heptanedionato,benzoylacetonato, 1,3-di-phenyl-1,3-propanedionato, dionato,1,3-cyclopentanedionato, 1,3-cyclohexanedionato,5,5-dimethy-l,3-cyclohexanedionato .and Z-acetylcyclohexanonato, and Lis selected from the class consisting of acetonitrile, propionitrile,and acrylonitrile.

3. A ruthenium complex according to claim 1 in which 1 the ligand L isselected from propionitrile, acetonitrile and acrylonitrile.

4. The ruthenium complex Ru(acac) (OH C-N) 3-methyl-2,4-pentane- 5 6 5.The ruthenium complex Ru(acac) (CH CH CN) References Cited Dwyer, etal.: Aust. J. Chem. 16 (1963), pp. 42-50.

PATRICK P. GARVIN, Primary Examiner A. P. DEMERS, Assistant Examiner US.Cl. X.R.

252431 P, 431 N, 431 R, 431 C; 260-370 R, 465.8

